Method of and apparatus for treating boiler feed-water.



H. C. HEATON.

METHOD OF AND APPARATUS FOR TREATING BOILER FEED WATER.

APPLICATION FILED DEC. 8. I914.

Patented Feb. 5, 191$.

WITNESSES:

/m ATTORNEYW,

HERMAN HEATUN, OF CHICAGO, ILLINOIS, ASSIGNOR, 1'0 THE BAJBCOGK &'WILC@TT. CQTTJPANY, 0F BAYUNNE, NEW ERSEY, A CORPORATION OF NEW JET-WET.

METHOD UT AND APPARATUS FUR TREATING BOILER FEED-WATER. I

Specification of Lettersfatent.

Patented Febs 5, thin.

Application. filed December a 1914. Serial Ito. $76,005.

To all whom it may concern:

Be it known that l, HERMAN C. HEATON, a citizen of the United States, residing at Chicago, in the county of Cool; and State of Illinois, have invented certain new and useful improvements in Methods of and Apparatus for Treating Boiler Feed-Water, of which the following is a specification.

My invention relates to a method of and apparatus for treating boiler feed water and will be understood from the following description taken in connection with the accompanying drawings in which Figure l is a diagrammatic side elevation of a plant showing one means for practising the invention; and Fig. 2 an enlarged cross-section of the intermediate tank.

In the patent of David S. Jacobus, No. 1,219,320 dated March 13, 1917, liability of corrosion. of an economizer is eliminated or minimized by first heating the feed water, then withdrawing it from the heating apparatus andpermitting air or other gases to escape before this water is fed to the eoonomizers or parts thereof, Tn that application the low pressure stage of an economizer is utilized for the initial heating of the water. My invention consists in further heating the feed water after it leaves the low pressure stage, and before it is fed into the high pressure stage; and in such an arrangement that the tank intermediate the two economizer stages may be usefully applied for absorbing the heat contained in the exhaust steam from the auxiliaries, or in the steam from any other source or sources -Referring to the drawings in which if show a preferred form of the invention, the numeral 1 designates a boiler and 2 the outlet flue for the gases. Suitably arranged to be acted upon by the gases is a two-stage economizer comprising a high pressure stage 3 and a low pressure stage 4, the tubes of both stages being connected to upper and lower boxes 5 and 6. The gases, after flowing over the economizer tubes, leave through the induced draft fan 7 from whence they pass through the uptake 8 and are finally led to the stack.

The water from the hot well is drawn through the pipe 9 into a pump 10 and fed thereby through pipe 11 into the low pressure stage 4 of the eoonomizen. From the low pressure stage the water passes through the pipe 12 into a tank 13 where it is heated and the air permitted to escape therefrom. The tank 13 is provided with a relief valve 14: and the air and gases allowed to escape through this valve, or they may pass through a separate connection let havingan ejector or air pump (not shown) to maintain the pressure below that of the atmosphere. The feed water, after being freed of air and gases, and after being heated in tank 13 by the means hereinafter described, flows through pipe 15 to pump 16 by which it is forced through pipe 17 into and through the high pressure stage 3 of the economizer, and through pipe 19 and feed valve 20 into the steam and water drum 18. It will be noted that the flow of the feed water through the economizer is in general in the reverse direction to the fiow of the gases over the surface of the economizer tubes. The counterflow thus obtained aids in economy, since the hottest gases act on the tubes carrying the hottest water. The steam for the pumps 10 and 16 is taken from the steam main 2i and conducted throughpipe 22 to the throttle valves 23 and 24. From these pumps the exhaust steam passes through pipe 25 to the heater tank 13.,

The purpose of the above described arrangement is twofold:

(1) To eliminate, in tank 13, air and gases contained in the feed water after the water has passed through the low pressure stage of the economizer so as to reduce or prevent pitting or corrosion of the tubes of the high pressure stage. As the pressure in the low pressure stage t of the economizer is comparatively low, said stage may be made of cast iron tubes which will' withstand interior corrosion through the presence of air or gas in the water,or this stage may be made up of tubes of thin metal and, by using tubes of the right diameter, and properly spacing them, the

- heat transferred from the gases to the tubes may be made maximum with a minimum draft loss, As the water flows through the tubes of the low pressure stage 4 it will be heated by the gases to a sullicient temperature to expel air and gases therefrom, the air escaping when the water is delivered to till lib

tank 13. This feature is fully described in the said Patent No. 1,219,320.

Also, by placing the tank 13 above the level of the low pressure economizer section,

ltd

the air and gases, liberated by the heating of the water in said section, will rise freely along with the water into the tank in the natural direction of the flow from the low pressure section, and thus freely enter the tank where liberation of the air and gases takes place. If any steam is generated in the low pressure section this too will rise with the water to aid in the natural upward direction of flow into the tank.

(2) To further heat the feed water after leaving the low pressure stage, and preferably in tank 13, so as to increase the total plant efiiciency over what would be possible in ordinary practice, the heating of the water may be effected by any suitable means, and for the purpose of illustrating one means I have shown the pipe 25 as conducting the exhaust steam from the pumps 10 and 16 to tank 13. The steam from other auxiliaries, such as the vacuum pump, forced blast apparatus, if one is used, or from one of the stages of a steam turbine, may be introduced to tank 13 through pipe 26.

In Fig. 2 I have shown an enlarged section of tank 13. The water which enters through pipe 12 flows into the uppermost of a series of horizontal pans 27 from which it overflows to other pans at successively lowerlevels, the purpose being to present a large surface of water to the steam which enters the tank through the pipes 25 and 26. A float regulating device may be employed to maintain a givenv water level in the tank.

It has heretofore been proposed to use exhaust steam from the main prime movers or auxiliaries to heat the feed water before it enters an economizer. When used in this way the heat from the exhaust steam is not wasted, but the efiiciency of the economizer, or the ability of the economizer to abstract heat from the waste gases, is materially lessened and a loss is thereby incurred. The reason for this is that the average temperature of the economizer and its contained water is made higher through the use of the exhaust steam, and the ability of the economizer to abstract heat from the gases is decreased because of lowering the mean dif-.v

ference in, temperature between the hot gases and the water in the economizer.

According to the present'invention I re turn the steam from the auxiliaries to the tank 13 intermediate the low and high' ressure stages of the economizer, and utilize it at this point for imparting additional heat to the feed water after it leaves the low pressure stage. The intermediate tank thus serves to transfer the heat in the steam from the auxiliaries to the feed water after it leaves the low pressure stage. Heating the feed water in tank 13 will not reduce the amount of heat that will be absorbed by the economizer to as great an extent as would be the case if the water were heated the same amount before it entered the low pressure stage. The temperature range, or the difference in the temperature of the hot gases and the water in the tubes, is one of the factors governing the amount of heat absorbed. Increasing the temperature of the water entering the low pressure stage by utilizing the heat in the exhaust steam would decrease the temperature range for the entire economizer, as it would cause an increase in the temperature of the water in both the high and low pressure stages and would therefore decrease the amount of heat 1 absorbed in both the high and low pressure stages. Heating the water in the tank between the stages would decrease the temperature range of only the high pressure stage and would cause a reduction of heat absorption in the high pressure stage only and therefore reduce the heat absorbed by the entire economizer to a less extent than should the given amount of heat from the exhaust steam be imparted to the water entering the economizer.

By the word pressure in some of the claims, as applied to the water in tank 13, I mean absolute pressure which may be either above or below that of the atmosphere.

What I claim and desire to secure by Letters Patent of the United States is 1. The method of treating boiler feed water consisting in passing the water through the low pressure stage of a plural stage economizer, withdrawm the water and any contained air or gases rom said stage and afterward allowing discharge of the air or gases therefrom, heating thls water by exhaust steam and then passing the water through a high pressure stage of the economizer and then into a boiler.

2. A steam boiler plant comprising a boiler, a plural stage economizer arranged to be heated by the waste gases from the boiler, a tank intermediate the two stages of the economizer arranged to allow free discharge of the air or gases from the water entering from the low pressure stage, the connection from the low pressure stage to the tank being arranged to allow any contained air or gases to pass along with the water into said tank, means for passin the water and any air or gases contained therein through the low pressure stage of the economizer and thence into said tank, means for heating the water in said tank by the introduction of exhaust steam and means for then passing the water through the other stage of the economizer and then into the boiler.

3. In combination, an economizer for treating boiler feed water comprising a plurality of stages made up of tubes through which the water is passed, means for heating said stages, a tank between two of the stages into which thewater with contained naaaiea air or gases flows after being heated in the a first stage to thereby permit the escape of absorbed air andv gases from the water, and means for further heating the Water in said tank by the injection of exhaust steam, and means for forcing the water from said tank through the remaining stage or stages of the economizer and then into the boiler.

4. A steam boiler plant comprisin a boiler, a plural stage economizer adapte to be heated by the waste gases of the boiler, a

tank intermediate the tWo stages of the economizer and located above the level of the low pressure stage, means for passing the water with any contained alr or gases through the low pressure stage of the economizer and thence upward lnto said tank, means for heating it in said tank by the introduction of exhaust steam and means for then passing the water through the other stage of the economizer and then into the boiler.

In testimony whereof I have hereunto signed my name in the presence of two subscribing witnesses.

HERMAN C. HEATON.

\Vitnesses:

vC. F. SARGENT,

R. J. STRASSER, 

